In the related art, a wireless tag is attached to an article such as a commodity or equipment in shops, warehouses, offices and the like, and a wireless tag communication device reads information stored in a memory section of the wireless tag in a noncontact manner to detect the presence of an article. Since information in plural wireless tags can be read in a short period of time, it is desirable to improve the efficiency of detection operation in such a device.
JP-A-2011-237941 discloses a wireless tag communication device that searches for a wireless tag having a specific ID number (identification information) by setting the identification information of the wireless tag to be searched therein and searching for this identification information among wireless tags in which different identification information is stored are respectively attached to a large number of articles.
However, if radio waves of a wireless tag are received through an antenna having a maximum directivity in a specific direction, a readable direction range of the wireless tag with respect to a direction of the antenna varies depending on a relationship between a transmission output of the wireless tag communication device and a position of the wireless tag. For example, when the transmission output power of the wireless tag communication device is large, neighboring wireless tags in a direction in which the directivity of the antenna is small are also read. In this case, a user recognizes that the wireless tag is present in the direction of the maximum directivity and searches the wireless tag while moving forward in the read direction. In the worst case, the wireless tag to be searched may be missed.